1. Field of the Invention
The present invention relates to a flat gasket-type seal for placement between machine parts, especially hydraulic control panels, to seal them relative to one another.
2. Description of the Prior Art
To seal hydraulic control blocks and similar machine parts relative to one another, it is known to introduce annular grooves in the metal surfaces that are to be sealed, and to insert O-rings into these grooves. This requires a very high surface finish in the annular grooves, and the O-rings must be positioned very precisely in the grooves. This takes a lot of time, and moreover involves a number of shortcomings, since the O-rings can, for example, slide around, or may not fit precisely in the annular grooves if the tolerances are too great. In addition, when servicing or repairs are undertaken, there exists the danger that different O-rings get mixed up, so that the wrong O-ring is installed. There is also the danger that the O-rings can move about in the annular grooves, so that during fluctuations in pressure or pressure peaks, the O-rings can be pressed into the gap between the two metallic surfaces and can be destroyed. This can occur, in particular, when the pressure in the hydraulic unit is rapidly reduced to zero from a pressure peak.
It is also known to provide a metal plate with holes in which appropriate O-rings are loosely inserted. The drawback to this is that the user must purchase, control, and assemble various parts namely the metal plate and the different O-rings, so that here also a not inconsiderable assembly effort must be carried out. At the same time, there exists a danger that the sealing rings can be mistakenly interchanged, resulting in unsatisfactory assembly of the unit. Since the O-rings are inserted loosely into the holes of the metal plate, a sudden drop in pressure in the hydraulic unit can draw the O-rings into the hydraulic system due to the partial vacuum that occurs. A further danger is that the medium is forced between the O-rings and the metal plate, for example during a brief leak or lack of sealing. Then, when the pressure increases, this thin oil film between the O-rings and the metal plate exerts a certain pump action, which can lead to further leakage. Furthermore, with such a loose arrangement in the metal plate, the O-rings are subjected to a certain amount of fluctuation of the periphery, so that it is not possible to assure a uniformly precise positioning.
An object of the present invention is to provide a flat gasket-type seal that avoids the aforementioned drawbacks, and that, with simple means, yields a flat, rubber-metal, gasket-type seal that is embodied as a one-piece, compact component.